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Advantages and dis-advantages of having wireless (Wi-Fi) as primary network

By Rajesh K

Since Wi-Fi has become a very popular standard now for network access at the edge level, this article looks to ponder if an all wireless office is a possibility. We will look at what all can be made wireless and what cannot, what are the advantages and dis-advantages of having wireless as a primary network. We will look at the following factors:

First, we will have to discuss to what level a wireless access can be implemented in an organization. Can we totally remove all the cables? No. Wireless, as of today is popular only in the edge network – For the end users to access the network through their laptops, PDA’s, PC’s etc. The backbone network is still wired. You need access points to be placed in ceilings for nearby users to access the wireless network. But these access points need to be connected to the wired LAN, a wired backbone. These LAN connections perhaps go to a distribution switch (which is again wired) and that is in turn connected to a Wireless controller and a Core switch in a data centre which is totally wired. So, in the whole enterprise, only the access layer can become fully wireless. But there are certain mesh networks which allow the access points to connect to each other through wireless – making the distribution layer wireless as well, but they are not very commonly seen.

Wireless (Wi-Fi) network have thus far been a secondary network – an overlay on the primary network which is essentially wired. So, it has been optional in a lot of organizations. Can the wireless network become the primary network at least in the access layer, thereby eliminating a huge part of the cables to your desktop? Let us see…

Cost: Wireless networks have an advantage of reduced cost. Not considering the running cost (which is also reduced), if you look at only the initial set up costs, every desk today has at least three ports – 2 for voice, data and one for redundancy. So, there are not only three cables coming to the desk but there are also three switch ports being allocated per desk. This will result in a large number of edge switches and consequently higher configuration of distribution switches as well. There are also the associated set up costs and passive components cost(racks, patch panels etc.) as well. Contrast this with the wireless network – You may need one access point every 15 to 20 desks. And perhaps one cable going back to a single port of the distribution switch. So, the cost reduction of a wireless network is huge. But there is one factor we need to include – the cost of the controllers and extra functionalities in a wireless network. This could run into considerable amounts, but will still be lesser than what it would take to implement the same functionalities in a wired network.

Redundancy(Edge level): Though one redundant port is provisioned for most of the desks, when there is a failure in cable or switch port, some manual intervention is required for the PC to connect back to the network. Contrast this with the wireless network: Mostly the wireless networks are over-configured and the users establish themselves dynamically to the access point with the maximum power and lower users. And, when an access point goes down, the user automatically re-establishes with another access point in the range. And there are always more than one AP in the range of every user as the access points have a good area of coverage – around 30 meters indoor(They can expand their coverage or contract it based on other access points).

Mobility: There are more mobile users now, than ever and they will keep increasing. These are the users who keep going from one office to another, one building to another, one floor to another etc. And people want to work from the canteen, lawn and what not. The higher management wants their desk to be free of cables, and many people work from multiple cubicles taking their laptops with them. These requirements are already met by the Wi-Fi networks. And port based VLAN’s of the wired network has always been slower to adopt to mobile personnel. Convenience has always been an important factor for adopting wireless networks.

Network Access Control: With wired network, one can group people and apply certain network access controls per group. You can decide who can browse the internet, who cannot, who can access the SAP server, who cannot and other such stuff. Some wireless networks also offer such controls for the wireless users. This was a challenge previously as one port provides access to many users but wireless networks have fast progressed and include such functionalities.

Inaccessible places: In a factory, for example, there have always been some places where it is tedious to get the wires into. There have also been some places like a security cabin where there is only one PC but a fiber cable needs to be run only for that purpose. In these places, the wireless network has always been advantageous and much cheaper.

Security: This is a tricky question. Even though the wireless vendors have integrated a lot of security mechanisms like centralized 802.1x authentication, encryption(WPA2), wireless intrusion/rogue access points detection and prevention, etc. people are very much bothered about their internal wireless signals going to the road. In a wired network, there are only a few points through which an intruder can take unauthorized access, but a wireless network is not so. But wireless security is getting better and safer with every passing day.

Bandwidth: This is another tricky question. I say tricky because, it is obvious that wired network can provide up to 1000 Mbps of bandwidth per system while wireless access points can provide a maximum of 300 Mbps (That too on a shared half duplex basis, IEEE 802.11n). Let us take the normal standard – IEEE 802.11a/g. The access points in this standard can provide up to 54 Mbps (practically around 27 Mbps) that is shared between around 15 systems. So, approximately 2 Mbps per user. The interesting point to note here is, even this bandwidth is enough for most of the applications that run today. Add IEEE802.11n – 300 Mbps per access point and you get much more with wireless networks. Isn’t that enough? All the 1GE ports to the desktop is an overkill. At Least now.

Printers / Fax / Photo copiers: Basically multi-function devices. These devices are commonly used with a cable, and perhaps need one too. But many vendors support Wi-Fi enabled multi function printers too. Users can connect to these printers (Print, scan, copy – three in ones) over the wireless network. But they are not very popular.

Real time applications (Video/Voice): Voice is always a challenge. IP phones just need a cable to the desk. Most of the IP phones come with a two port in-built switch which can be used to connect the PC as well. But to counter this challenge – wireless vendors are advocating Voice over Wireless LAN handsets which are like your cell phones, but work with your IP PBX and Wi-FI network. It is actually a carry-able desk phone. There is another interesting solution being proposed – FMC (Fixed Mobile Convergence) where the dual-mode handsets (Cellular and Wi-Fi) would be used and when the employee is in the company, they would connect to the Wi-Fi/IP PBX network but once outside, they would connect to the cellular network. The switch over could take place automatically. But these approaches are quite expensive(as everyone needs to have a dual mode cell phone, and not all phones are compatible in some cases) and we don’t know how much of this the users would prefer.

Video has always been accepted more readily. The IP Surveillance cameras have long since been wireless (Wi-Fi) enabled and wireless systems incorporate QOS (Quality of Service) parameters for delay sensitive traffic which ensures priority for voice and video packets. Companies are trying out the wireless surveillance system as it could save a lot of cabling expenditure. But it still has a long way to go. Professional video conferencing applications have not supported Wi-Fi connectivity (except for connecting your laptop to make presentation) to the network. So maybe some cables need to come in after all.

Dense deployment: Wireless networks performed poorly in dense deployments such as a class room or a huge conference hall because of radio/channel interference. But today’s wireless networks are handling this issue in a much more controlled way, and doing a good job enabling them.

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There are lots of vendors shipping Wi-Fi Only handsets. From D-Link at the low-end to Ascom, Vocera and Polycom at the high end its about a $~500M market already. Dual mode phones are estimated to be around 300M units by 2011

I was aware of Dlink and Polycom, but thanks for sharing the other two vendor names… I guess Polycom bought Spectralink…